Sorry if this turns out to be off-topic. Well, it's computer related although it's mostly coding and not hardware hacking...

I carry with me a Garmin GPS and often have it running and recording while I go to walks, hikes, bike rides, and even when commuting to work. I wrote some Perl scripts to visualize accumulated data, color coded for speed. Here is how the area around my home looks like:

Here RED is driving, GREEN is bikind, and BLUE is walking/hiking. Makes a pretty desktop wallpaper. More images and a video are available here:

In case you have some GPS logs yourself and want to give it a try, the scripts can be downloaded from the same page. Please, let me know if you have any problems with the scripts - they should work for most GPS devices.